In the manufacture and distribution of pressurized containers, it is often necessary to detect the rate at which gas leaks from the containers. The characterization of leak rates is especially important in the manufacture of pressurized containers for medication, such as inhalers. Here, leak rates can impact such metrics as the number of dosages, expiration dates, and efficacy. Over time, loss of propellant from a metered dose inhaler (MDI), for example, can result in increased concentrations of the active ingredient, leading to a larger than intended drug quantity being administered.
In the past, infrared spectrometry has been used to estimate leak rates of inhalers. The gases leaking from inhalers were passed through the sample cell of an infrared spectrometry system. From this information, the leak rates could be estimated.